This invention relates generally to a fluid system, and more particularly, to a method and apparatus for determining the status of a relief valve associated with the hydraulic system.
Over a period of time, the relief valve located in a hydraulic circuit on an earthmoving machine needs to be calibrated. Calibration is necessary to ensure that the pressure within a circuit does not exceed a maximum pressure. If the actual pressure does exceed a maximum pressure then the hydraulic circuit, such as the cylinders, pumps and work implements, may be damaged. On many earthmoving machines that use hydraulic systems to power the implement system, it is difficult for mechanics to check the relief pressure setting of the hydraulic circuit. Preferably the status of the pressure relief valve is checked without moving any work implements. In a service area, for example, the implements may not be able to be moved because of space constraints, or possible damage from operating in a confined area. In many cases the only way to check the hydraulic circuit relief pressure is to disconnect one or more hydraulic hoses and insert specially designed gauges to determine the status of the relief valve. This is a time consuming task and since the hydraulic system has to be opened up, often in a dusty environment, it frequently causes contamination in the hydraulic system.
The present invention is directed to overcoming one or more of the problems identified above.
A method for determining a status of a relief valve located within a fluid system is disclosed. The method includes the steps positioning an actuator valve in a closed position, deactivating a pressure compensation assembly; thereby deactivating the bypass flow; and sensing a relief pressure of the system.
In yet another aspect of the present invention, an apparatus adapted to determine a status of a relief valve located within a fluid system is disclosed. The fluid system includes a pump and an actuator valve, and is located on an earth moving machine. The apparatus includes a pressure compensation assembly adapted to receive a pressure compensation command and responsively control the fluid pressure of the system; a pressure sensor adapted to sense the pressure of the fluid within the circuit and responsively generate a pressure signal; and a controller adapted to receive the pressure signal, deliver an actuator valve command to the actuator valve thereby placing the actuator valve in a closed position, deliver said pressure compensation command to said pressure compensation assembly, thereby placing the assembly in a deactivated position, and determine a pressure of said fluid in response to said pressure signal.